The present disclosure relates to a semiconductor structure, and particularly to a GaN-based light emitting diode employing an elemental semiconductor material contact and methods of manufacturing the same.
Gallium nitride (GaN) is a III-V compound direct band gap semiconductor material having a wide band gap of 3.4 eV, and thus, allows useful applications in various optoelectronic devices. Gallium nitride is commonly used in light-emitting diodes.
However, one of the challenges for the gallium nitride based light emitting diodes is a large contact area required on a p-doped gallium nitride portion as well as limited thermal budget for formation of metalized contacts after formation of a multi-quantum-well structure. The large area requirement for a contact to a p-doped gallium nitride portion makes it difficult to provide a high-efficiency gallium nitride based light emitting diodes because the opaque metallic material employed for the contact to the p-doped gallium nitride portion blocks a significant portion of light emission from the multi-quantum-well in the light emitting diode.
Specifically, because a p-type gallium nitride material does not provide high conductivity, electrical current does not spread well within a p-doped gallium nitride portion of a light emitting diode. In order to enhance light emission from a multi-quantum-well, therefore, a contact structure to the p-doped gallium nitride portion needs to provide sufficient current spreading. A high degree of current spreading can enhance light emission by minimizing the turn-on voltage and by reducing the series resistance within the light emitting diode. However, the contact structure to the p-doped gallium nitride portion includes a metallic material that blocks light emission from the multi-quantum-well, thereby decreasing the efficiency of the gallium nitride-based light emitting diode.